Tens of thousands of masked protesters marched through Hong Kong on Sunday in defiance of a colonial-era emergency ban on wearing face masks in public. CNN reports that at one point, a man driving at taxi mowed down a group of protesters. It was not immediately clear if anyone was injured. Photos of a bloodied man being severely beaten were also posted on social media on Sunday, though it was not clear who the man was or what side of the unrest he was on. Reuters reports that the protesters face one year in prison for hiding their faces under the new ban, which was instituted by Hong Kong leader Carrie Lam earlier in the week came into effect on Saturday. Police warned Sunday that they would begin “dispersal operations on Hong Kong island,” and warned people off the streets. “Members of the public are advised to stay indoors and keep their windows shut.” The demonstrations mark 18 weeks of unrest in the city.